I loved making The Imitation Game and it's really gratifying to hear the audience's response to the character that I play. It was just a little thing that I did because I really liked the film and I liked Benedict [Cumberbatch] and I loved Morten's [director Morten Tyldum] previous film, Headhunters. For me, it was something I did thinking, "Wow, this is a lovely quality piece of work."

Rowan Joffe was on top of everything. He knew exactly how he wanted everything to be, right down to the fact when I made those telephone calls, I didn't do it afterwards in a studio. I think that's how he operates. He likes it to be as real and as clear as possible.

And I think in your 40s, you land a little bit, physically and mentally, you arrive at a place where you feel you've learned some stuff. Having children at that point meant I had something very useful to do for the next 20 years.

Interestingly, this character [Doctor Nash] is probably closer to me than somebody like the evil Sir Godfrey in Robin Hood or Lord Blackwood who wants to take over the world in Sherlock Holmes. This is a character that's English, he's based in London, and so it's closer to me than a lot of stuff I've been doing recently.

It's great to have the chance to play a character before he goes to the dark side, or the yellow side if you will. Normally, you don't get that opportunity. The narrative of a movie usually demands that you are that guy from the start.

I think it serves the purpose of the film if the premise is that you're unsure of me because you've only ever really seen me play villains.

I had this extraordinarily bizarre moment when, two Fridays ago, my missus gave birth to our second child at 11am and by the same time the following day I was sitting around a table with Ridley Scott, Russell Crowe and Leonardo DiCaprio in Rabat in Morocco, rehearsing a scene we were going to shoot the next day.